Electric circuit breaker



Jan. 9, 1951 w. G. BOURNE ELECTRIC CIRCUIT BREAKER 2 Sheets-Sheet 1 Filed Jan. 26, 1948 Fig.1

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Patented Jan. 9, 19 51 ELECTRIC CIRCUIT BREAKER William George Bournc, Acton, London, England, assignor to Rotax Limited, London, England Application January 26, 1948, Serial No. 4,272 In Great Britain December 16, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires December 16, 1966 2 Claims.

improved electric circuit breaker of simple and robust construction.

In the accompanying drawings,

Figure l is a front elevation, partly in section, of a three-phase circuit breaker constructed in accordance with the invention;

Figure 2 is a sectional side elevation of the circuit breaker;

Figure 3 is a fragmentary side elevation showa part of the closing toggle mechanism.

In one convenient embodiment of the invention as ill'istr tedin a three-phase alternating current circuit breaker there is provided a body or base i of suitable insulating material and on this are secured three A red contacts 2. Adjacent to these contacts is arranged an arm 3 which is pivoted at one end at 4 to brackets 5 secured on the body part i and the said arm at the other end carries three corresponding movable contacts The latter may be mounted directly On the arm, but preferably they are carried by spring-loaded ringers i pivotally mounted on the arm at 8. Flexible conductors 9 connect the contact arm 3 to terminals on the base. For moving the arm it to its closed position there is provided a toggle l'nk device which comprises links H and E2 pivoted together on a pin E3, the links being referably dupl cates. The outer end of the link H is pivotally attached to the arm 5 at it, and the outer end of the link 52 is pivotally attached at E5 to one end of a lever it which itself is cartried on the brackets 5 by a pivot 57 situated between the ends of the lever. The toggle links are loaded by a pair of helical springs it which bear at one end on sub-brackets it on the main brackat the other end on collars 2 secured {S which are pivoted at 25 to the arm In on with the toggle links ii, E2 is arranged an electroniagnet 22 of the solenoid type the plunger 23 of which is connected by a link l with the "motion iii of the toggle links, the said being formed with a slot of suitable length to provide a lost-motion connection with the toggle links. Also at the electroinagnet side of these links is arranged a spring stop-blade ii which may (and preferably) fOlll part of a swi ch having contacts 25 for controlling the circuit of the winding of the electroniagnet 22,

and which also serves the purpose hereinaiter described. Tl'e blade 25 is arranged to be actuated by a roller 28 on an extension of the pivot l3 joining the two toggle links.

A second toggle device is provided comprising links 22' and 28 pivoted together at 29 and loaded by a spring so. The outer end of link .28 is pivotally mounted at 3| on a bracket secured to the body or base and the outer end of the link 21 is pivotally connected at 32 to the other end of the lever H5. Adjacent to the junction of these links is mounted a spring blade 33 which at one end bears on the link 22! and at the other end is anchored to the link 2%. It will be understood that the links 2?, 28 are preferably duplicated and are connected by the common pivot pin Also in association with these links is arranged a spring loaded trip levertd pivoted at 35 and carrying a stud ('36 arranged to bear upon the pivot pin Elli. The free end of this lever ti l is connected to the plunger ill of a second electromagnet 38 of the solenoid type. Wind; gs 39 in series with the main switch contacts surround cores t8 arran ed to act upcnan armature ll ca l ed on a pivoted lever 152 of be1lcrank form, one arm of which en ages a pair of so"- ng "blades 33 one of which carries a movable contact 43 for engagement with a fixed contact id when the lever is actuated. These contacts are in the circuit of the electromagnet A push button 35 is also provided engaging a bell-crank lever 35 pivoted at ll and loaded by a sp ng ii. The other arm of this lever comprises a pair of parallel members 3 arranged, when the button i5 is depressed, to engage th pivot pin 29 of the second toggle device.

A circuit breaker as described above may be closed by a manually operable switch of, for example, the push button type arranged in the circuit of the electromagnet 22 connected to the first toggle device. When the breaker is open as illustrated, the toggle links H and E2 occupy a, V relationship and the links 2?, 28 of the second toggle device are almost in alignment n th each other, being in, fact slightl beyond their dead-centre position and being maintained in this condition by the spring blade 33 which acts on them. The links are prevented from further outward movement in a direction to break the toggle by the spring blade In this position the links 2?, 28 provide an anchorage for the lever I6 Which is thereby held in stationary relation to the fixed bracket structure. To close the breaker the appropriate switch is actuated for closing the circuit of the electromagnet By the action of this electromagnet the toggle links ll, I2 are straightened out and moved slightly beyond their dead-centre position, causing the contact arm 3 to be rocked to the closed position and bringing the main contacts 6 into engagement with their associated fixed contacts. This action brings the roller 26 into engagement with the spring blade 25 and breaks the contacts 25 which interrupt the circuit or the electromagnet 22, so that the closing of the breaker requires only a momentary operation of the electromagnet. On interruption of the elec'troma'gnet circuit the p'lunger 23 returns to its initial position without afiecting the toggle links, by reason of the lost motion afforded by the slot in the link 24. w

To open the breaker the push button 45 is depressed. This causes the arms 48 of the lever 46 to engage the pivot pin 29, thereby collapsing the links 21, 28 of the second toggle device and causing them to assume a V relationship. As a result the lever I6 connecting the two toggle devices is released so that the toggle links ll, 2

no longer have a fixed anchorage at Hand the toggle is broken. This is effected by the combined action of the spring blade 25 which urges the links to the opposite side of their dead-centre position and the helical springs l8 which rock the arm 'Sto aposition in which the main contacts are opened. Upon release of the push button 45, the spring 30' acting on the toggle links 2'!- and 28 restores these and the lever It to their initial position, and the breaker is thenin condition to be re-closed when required.

In the event of an overload, the armature 41 is actuated, thereby causing the circuit of the electromagnet 38 to be closed to actuate the latter and thereby result in the coll-aps'ing of the second toggle device and initiating the sequence of actions involved in the opening movement of the breaker described above. It will be appreciated that a push button or other switch may be provided in place of or in addition to the push button 45, such switch being arranged in an appropriate circuit for energising the second electromagnet 38 to effect the opening of the breaker when required.

Having thus described my invention which I claim as new and desire to secure by Letters Patent is:

1; An electric'circuit breaker comprising in combination at least one fixed contact, at least one movable contact, a pivoted arm carrying the movable contact, a lever pivoted at a, position intermediate" its ends on a fixed axis, a pair of spring loaded toggle links respectively pivoted at their opposite ends to the arm and one end of the lever, means for actuating the toggle links to move the arm in the direction for closing the contacts, a second pair of spring loaded toggle links which at their opposite ends are respectively provided with a fixed anchorage and pivoted to the other end of the lever, and means including an electromagnet for actuating thesecond toggle links to move the arm through the medium of the lever and the first mentioned toggle links in the direction for opening the contacts.

2. An electric circuit breaker comprising in combination at least one fixed contact, at least one movable contact, a pivoted arm carrying the movable contact, a lever pivoted at a position intermediate its ends on a fixed axis, a pair of spring loaded toggle links respectively pivoted at their opposite ends to the arm and one end of the lever, an electromagnet for actuating the toggle links to move'th'e arm in the' directionzfor' closing the. contacts, said electromagnet having a lostmotion connection with the toggle links, a switch operable by the toggle links for controlling the electromagne't, a second pair of spring loaded toggle linkswhich at their opposite ends are respectively provided with a fixed anchorage and pivoted to the other end of the lever, and means including a second electromagnet for actuating the second toggle links to move the arm through the medium or the lever and thefirst mentioned toggle-links in the direction for opening the contacts.

WILLIAM GEORGE BOURNE.

REFERENCES oiT En The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,663,680 Copley 1 Mar. 2'7, 1928 1,999,410 Graves, Jr., et a1. Apr.30, 1935 FOREIGN PATENTS Number Country Date 128,181 Austria Mar. 10, 1932 302,042 Germany Feb. 10, 1917 415,413 Great Britain Aug. 21, 1934 

